Integrated transcriptomics, proteomics, and pathway enrichment analysis in the spleen and skin of chickens reveal tissue-specific roles for the Marek’s disease virus conserved herpesvirus protein kinase

Conserved herpesvirus protein kinases (CHPK) are conserved among the Orthoherpesviridae. Marek's disease virus (MDV) CHPK is dispensable for replication in chicken splenocytes but essential for replication in epithelial skin cells, where the virus is shed. We hypothesized that 1) MDV alters cellular gene expression in both tissues, 2) the responses differ between the spleen and skin, and 3) CHPK regulates these responses. To test these hypotheses, we collected spleen and epithelial skin tissues from chickens infected with wild-type MDV (vCHPKwt) or a CHPK-null MDV (vΔCHPK). RNA sequencing revealed significant differences in cellular gene expression between mock- and vCHPKwt-infected tissues. Pronounced differences were noted in the spleen, while the skin exhibited minimal changes. Functional enrichment analysis revealed that vCHPKwt infection significantly impacted the immune response, membrane transport, cell cycle regulation, and metabolic processes in both tissues. Comparisons between vΔCHPK and vCHPKwt in the spleen showed alterations in cellular interactions and immune system pathways. Global and phosphoproteomic profiling using mass spectrometry in the skin uncovered significant post-translational modifications of immune and energy regulators. Our findings demonstrate that CHPK plays a vital role in regulating cellular processes in the spleen at the transcriptional level while having a lesser impact on gene transcription in skin cells. Instead, CHPK influences cellular pathways post-transcriptionally, likely through protein phosphorylation. This study provides important insights into the mechanistic significance of CHPK during herpes viral replication in the natural host and during horizontal transmission.